The present invention is in the field of insulating glazing unit (“IG unit”) manufacturing. IG units have at least two spaced-apart, parallel panes. A peripheral spacer, typically formed of metal and/or plastic, is commonly provided between the panes adjacent their peripheral edges to maintain the panes in a spaced-apart configuration.
Conventional spacers are often provided in hollow, tubular form. In such cases, the spacer may have side walls adhered to the confronting inner pane surfaces. The spacer may extend all the way around the perimeter of the IG unit.
To seal the edges of the IG unit, one or more sealants are usually provided between the panes and the sides of the spacer. In addition, sealant is commonly applied over the outside face of the spacer. The resulting sealant arrangement provides resistance to water vapor and unwanted atmospheric gas permeating into the between-pane space(s) of the IG unit. In addition, if the between-pane space is filled with thermally insulative gas, the seal provides resistance to such gas escaping from the between-pane space. Known sealant materials include polyisobutylene (PIB), silicone, a combination of PIB and silicone, and various other materials.
The sealant beads that form the sealant arrangement may be applied by dispensing the sealant from nozzles. The resulting sealant arrangement may provide a seal around the perimeter of the IG unit. The sealant arrangement may, together with any spacer, extend from the inner surface of one pane to the inner surface of an adjacent pane. In some cases, the sealant around the perimeter of the IG unit entirely covers the outside face of the spacer, thus encapsulating the spacer between the panes.